Dial and digital indicators are measuring instruments used to accurately measure small distances and changes in dimensions, typically in engineering and manufacturing applications. They are often used in conjunction with other measurement tools, such as micrometers and height gauges, to provide precise measurements.

Dial indicators, also known as dial gauges or dial test indicators, use a needle or pointer attached to a spring-loaded plunger to measure small distances. The plunger is depressed or extended by the surface being measured, and the resulting movement of the needle is read on a graduated dial. Dial indicators can be either analog or digital, with digital dial indicators displaying the readings in a digital format.

Digital indicators, also known as electronic indicators or digital probes, use electronic sensors to provide highly accurate measurements. They can display measurements in a digital format, making them easier to read and record. Digital indicators can also be programmed to perform various functions, such as zero-setting, inch/metric conversion, and data output to a computer.

Dial and digital indicators are available in a wide range of sizes and accuracy levels to suit different applications. They are commonly used to measure the runout of machine parts, check the alignment of components, and determine the accuracy of machining operations. Some models of digital indicators can also be used for statistical process control (SPC) applications, where they can be integrated with computer software to monitor and control manufacturing processes.